Modular hip prosthesis

ABSTRACT

A modular hip prosthesis, comprising: (a) a proximal segment including a neck lockingly engageable with a femoral head component and a male tapered portion; (b) a distal segment having a proximal end and a distal tip, the distal segment further formed with a male tapered portion adjacent the proximal end thereof; and (c) a metaphyseal segment having a proximal end and a distal end, the metaphyseal segment preferably including a bone engaging outer surface portion, and further including an axial bore therethrough, the axial bore including first and second female tapered portions formed adjacent the proximal and distal ends thereof, respectively. The first female tapered portion of the metaphyseal segment is dimensionally configured to lockingly engage the male tapered portion of the proximal segment. The second female tapered portion of the metaphyseal segment is dimensionally configured to lockingly engage the male tapered portion of the distal segment. Optionally, a screw dimensionally configured to pass through aligned bores in the proximal, metaphyseal and distal segments is threadably engaged with a threaded bore formed in the proximal end of the distal segment.

RELATED APPLICATION

This application is a Continuation application of U.S. Ser. No.09/524,341, filed Mar. 13, 2000 now U.S. Pat. No. 6,319,286.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to the field of total hiparthroplasty, and, more particularly, to a three segment modular hipstem that allows full size interchangeability between component parts,yet provides superior resistance to component disengagement during use.

Modularity in total hip arthroplasty design is an evolving concept thatis receiving increased citation in the clinical literature. Theadvantages of these systems include off the shelf flexibility forcustomizing proximal and distal canal filling, as well as accommodatingdifficult situations of proximal deformity and bone loss. These designs,however, raise concerns that include structural compromise at themetal-metal interconnections due to stresses and intercomponentdisengagement.

To address these concerns, the present invention, in summary, provides amodular hip prosthesis comprising the following components: (a) aproximal segment having an axial bore therethrough, the proximal segmentincluding a neck lockingly engageable with a femoral head component, andfurther including a male tapered portion extending distally of saidneck; (b) a distal segment having a proximal end and a distal tip, thedistal segment further being formed with a male tapered portion adjacentthe proximal end thereof; and (c) a metaphyseal segment having aproximal end and a distal end, the metaphyseal segment including a boneengaging outer surface portion, and further including an axial boretherethrough, the axial bore including first and second female taperedportions, the first female tapered portion located adjacent the proximalend of the metaphyseal segment and dimensionally configured to lockinglyengage the male tapered portion of the proximal segment, the secondfemale tapered section located adjacent the distal end of themetaphyseal segment and dimensionally configured to lockingly engage themale tapered portion of the distal segment.

The male and female tapered portions of the corresponding proximal,metaphyseal and distal segments each comprises a conical sectionblending into a generally parabolic-shaped section. The blended conicaltaper/parabolic taper geometry of each tapered portion ensuressufficient taper contact area, and decreases the interfacial contactstresses and internal body stresses under bending loading of themale/female taper junction. The conical tapered sections each have taperangles ranging from about 1° to about 2.5° to provide enhanced torsionalresistance at the taper junctions. The proximal segment is lockinglyengageable with the proximal end of the metaphyseal segment to align theaxial bores formed through the proximal and metaphyseal segments. Theproximal end of the distal segment is lockingly engageable with thedistal end of the metaphyseal segment to align the axial bores formedthrough the distal and metaphyseal segments.

Optionally, the proximal segment is formed with a throughbore, and thedistal segment is formed with a threaded bore adjacent the proximal endthereof. These bores are alignable with the axial bore of themetaphyseal segment. A screw, dimensionally configured to pass throughthe aligned bores, is threadably engaged with the threaded bore formedin the distal segment to further enhance locking engagement of theprosthesis components if desired.

The present invention provides the following advantages: (a) superiorresistance to component disassociation by increasing taper contact areaand reducing contact stresses due to bending and torsional loads at thetaper junctions; (b) intraoperative flexibility through its modularity;(c) full interchangeability of any segment with any other segment; (d)adjustability of each segment for anteversion and retroversionindependent of the position of other segments, thus allowing a universaldesign for left and right hip applications; (e) independent selection ofleg length and offset of the prosthesis; (f) primary and revisionapplication with the same system; (g) allows the surgeon to tailor thedevice to the anatomy of the patient even in the face of a revisionsurgery that might leave a bone deficit; and (h) the use of all stylesand sizes of femoral head components.

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate the detailed description and preferredembodiments of the invention, and together with the detaileddescription, serve to explain the principles of the invention. It is tobe understood, however, that both the drawings and the description areexplanatory only and are not restrictive of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, perspective view of one embodiment of the modularhip prosthesis of the invention.

FIG. 2 is a cross-sectional, side elevation view of one embodiment ofthe proximal component of the invention.

FIG. 3 is a cross-sectional, side elevation view of one embodiment ofthe metaphyseal component of the invention.

FIG. 4 is a transverse cross-sectional view of one embodiment of themetaphyseal component of the invention taken along lines A—A of FIG. 3.

FIG. 5 is a cross-sectional, side elevation view of one embodiment ofthe distal component of the invention.

FIG. 6 is a transverse cross-sectional view of one embodiment of thedistal component of the invention taken along lines B—B of FIG. 5.

FIG. 7 is a cross-sectional, side elevation view of the engagedproximal, metaphyseal, and distal components of one embodiment of themodular hip prosthesis of the invention.

FIG. 8 is a cross-sectional, side elevation view of the proximal,metaphyseal, and distal components of FIG. 7 showing illustrative taperand blend dimensions.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-8, wherein like reference numerals are used toidentify like components throughout the various views, a firstembodiment of the modular hip prosthesis of the invention is showngenerally at 10. As shown in FIG. 1, hip prosthesis 10 generallyincludes: (a) a proximal segment 12; (b) a metaphyseal segment 14; and(c) a distal segment 16. A threaded screw 18 may optionally be used toenhance locking engagement of segments 12, 14, and 16 as describedbelow. As here embodied, proximal segment 12, metaphyseal segment 14,and distal segment 16 are each constructed as separate parts. As aresult, the segments may each be sized independently of one another.Such independent sizing capability gives the prosthesis modularity—thatis, it provides the surgeon with a wide selection of prosthesisconfigurations to accommodate virtually every anatomical conditionencountered during surgery. Advantageously, the modular prosthesis 10 ofthe invention may be implanted using well known bone cement implantationtechniques, or, in the alternative, may be implanted in an uncementedmode, using bone engaging surface applications well known to personsskilled in the art.

Referring now to FIG. 2, proximal segment 12 includes a neck 20 formedwith: (a) an angularly offset arm 21 terminating in a male taperedcolumn 22; (b) an extension member 24 extending distally of neck 20formed with a male tapered portion 25, and terminating in a cylindricalnipple 26; and (c) a segmented bore 27 formed through neck 20, extensionmember 24, and nipple 26. Preferably, proximal segment 12 is constructedfrom a biocompatible, high strength titanium alloy. However, proximalsegment 12 may be constructed from other biocompatible materials such ascobalt chromium alloy, stainless steel, and composite materials. Theouter surface finish of proximal segment 12 is preferably polished, witha surface roughness average of 32 microinches or less as determined byprofilometry. The outer surface finish may also be smooth matte ormachined using surface preparation techniques well known in the art.

Tapered column 22 of proximal segment 12 is dimensionally configured forlocking engagement with the complimentary female tapered portion of afemoral head component (not shown). One skilled in the art will readilyrecognize that proximal segment 12 may be constructed to accommodate allstyles and materials of femoral head components. An undercut 23 isformed in arm 21 and column 22 on each side of proximal segment 12 toincrease the range of motion between neck 20 and the acetabularcomponent (not shown) of a total hip joint replacement system, and tofacilitate engagement of a femoral head removal tool (not shown) when itis necessary to disassemble the femoral head from proximal segment 12during repair or revision of hip prosthesis 10.

As preferably embodied, tapered portion 25 of extension member 24comprises a male conical tapered section 25 a blending into a generallyparabolic-shaped male tapered section 25 b having a blend radius R2 ofabout 0.25 inch (see FIGS. 2 and 8). The parabolic geometry of taperedsection 25 b decreases the interfacial contact stresses and internalbody stresses under bending loading between tapered portion 25 andcomplementary female tapered portion 33 of metaphyseal segment 14(described below). As preferably embodied, the conical taper section 25a has a taper angle ranging from about 1° to about 2.5° to provideenhanced torsional resistance at the proximal/metaphyseal taperjunction. In the illustrative embodiment of the invention shown in FIG.8, conical tapered section 25 a has a length of about 0.43 inch, andparabolic tapered section 25 b has a length of about 0.09 inch. Forthese illustrative taper lengths, the ratio of parabolic taper length toconical taper length is about 21%. As preferably embodied, the parabolictaper/conical taper length ratio should range from about 5% to about30%. This range ensures sufficient taper contact area, and minimizes thepresence of sharp corners on the parabolic tapered section 25 b whichcan lead to high point contact stresses at the proximal/metaphysealtaper junction when the prosthesis is subject to bending stresses. Aspreferably embodied, the conical tapered section 25 a has a blend radiusR1 of about 0.09 inch (see FIG. 8). The complementary conical taperedsection 33 a of female tapered segment 33 has a blend radius R3 of about0.05 inch. These differing radii create a reduced stress condition atthe proximal/metaphyseal taper junction in the vicinity of gap G (seeFIG. 7) that is created when the proximal and metaphyseal segments arejoined. Advantageously, the same geometries and radii for taperedportions 25 and 33 can be used for all sizes of proximal segment 12 andmetaphyseal segment 14, thereby enhancing size interchangeability, andthus modularity, between the proximal and metaphyseal segments.

As preferably embodied, nipple 26 has a length of about 0.18 inch toincrease the moment arm of extension member 24 (see FIGS. 2 and 8), andthereby, assist in unloading the proximal/metaphyseal taper junctionupon inducement of bending stresses in the prosthesis. As with the tapergeometries and blend radii described above, the same length for nipple26 can be used for all sizes of proximal segment 12. Nipple 26 isdimensionally configured smaller than the diameter of sections 32 a, 32b and 32 c of throughbore 32 in metaphyseal segment 14 (described below)so that, when extension member 24 of proximal segment 12 is slidinglyreceived in throughbore 32 upon assembly of the prosthesis components(see FIG. 7 and discussion below), nipple 26 will not initially engagethe sidewall of bore 32. Upon application of sufficient load to thefemoral head of the prosthesis (not shown), nipple 26 will contact thesidewall of intermediate bore segment 32 b of bore 32, and thereby,transfer a portion of the induced bending stress away from theproximal/metaphyseal taper junction.

Referring again to FIG. 2, segmented bore 27 of proximal segment 12includes a first straight section 27 a, a tapered intermediate section27 b, and a second straight section 27 c. As preferably embodied,section 27 b tapers inwardly toward bore section 27 c at an angle ofabout 60°. Bore sections 27 a, 27 b and 27 c are dimensionallyconfigured to allow screw 18 to pass through proximal segment 12. Boresection 27 a also acts as a countersink for the head of screw 18, andshould be dimensioned large enough to comfortably accommodate amechanical driver such as a screw driver or drill bit to threadablyengage screw 18 with threaded bore 42 formed in distal segment 16(discussed more fully below) when screw 18 is used as part of theprosthesis 10 assembly.

Referring now to FIG. 3, metaphyseal segment 14 has a proximal end 14, adistal end 14 b, and is configured with a trapezoidal truncatedpyramidal section 30, integrated with a conical section 31. As shown inFIG. 4, this profile presents itself in transverse cross-section as agenerally trapezoidal section 36 offset from a generally circularsection 35. Alternatively, the pyramidal section 30 may be constructedso that the metaphyseal segment 14 has a generally rectangulartransverse cross section offset from a generally circular transversecross section. Metaphyseal segment 14 is preferably constructed from abiocompatible, high strength titanium alloy, but may also be constructedfrom other biocompatible materials such as cobalt chrome alloy,stainless steel, and composite materials. Metaphyseal segment 14 alsoincludes a bore 32 comprising proximal bore section 32 a, intermediatebore section 32 b, and distal bore section 32 c. Referring to FIGS. 3and 8, bore segment 32 a is formed with a female tapered portion 33comprising a conical tapered section 33 a blending into a generallyparabolic-shaped tapered section 33 b. Female tapered sections 33 a and33 b are complementary to male tapered sections 25 a and 25 b,respectively, of cylindrical section 24. As here embodied, conicaltapered section 33 a has a taper angle ranging from about 1° to about2.5°, a length of about 0.50 inch, and a blend radius R3 (referred toabove) of about 0.05 inch. Parabolic tapered section 33 b has a lengthof about 0.09 inch, and a blend radius R4 of about 0.25 inch (see FIG.8). For the foregoing illustrative taper lengths, the ratio of parabolictaper length to conical taper length is about 18%. Tapered sections 33 aand 33 b are dimensionally configured to lockingly engage taperedsections 25 a and 25 b, respectively, upon insertion of cylindricalsection 24 into bore 32. As with tapered sections 25 a and 25 b ofcylindrical section 24, the parabolic taper/conical taper length ratiofor tapered sections 33 a and 33 b should range from about 5% to about30% to ensure reduced contact stresses and internal stresses in theregion of the proximal/metaphyseal taper junction. Also, as discussedabove with respect to proximal segment 12, the same taper geometries andblend radii for tapered sections 33 a and 33 b can be used for all sizesof metaphyseal segment 14 to enhance interchangeability of the proximaland metaphyseal components, and thereby, modularity of the prosthesis10.

Referring again to FIGS. 3 and 8, bore segment 32 c of metaphyseal bore32 is formed with tapered portion 34 comprising a conical taperedsection 34 a and a generally parabolic-shaped tapered section 34 b.Tapered sections 34 a and 34 b are dimensionally configured to lockinglyengage the corresponding male tapered sections 43 a and 43 b of distalsegment 16, respectively, upon insertion of proximal end 16 a of distalsegment 16 into bore 32 of metaphyseal segment 14 (as more fullydiscussed below). As here embodied, the conical tapered section 34 a hasa length of about 0.51 inch, a taper angle ranging from about 1° toabout 2.5°, and a blend radius R5 of about 0.50 inch. Parabolic taperedsection 34 b has a length of about 0.09 inch and a blend radius R6 ofabout 0.25 inch (see FIG. 8). For the foregoing illustrative taperlengths, the ratio of parabolic taper length to conical taper length isabout 18%. As with the other tapered portions of the prosthesis 10discussed above, the parabolic taper/conical taper length ratio shouldrange from about 5% to about 30% to ensure sufficient taper contact areaand minimize high point contact stresses at the proximal/metaphysealtaper junction. Also, as with the other tapered portions describedabove, the same taper geometries and blend radii for tapered sections 34a and 34 b can be used for all sizes of metaphyseal segment 14 toenhance interchangeability of components, and thereby, modularity of theprosthesis 10.

The geometry of metaphyseal segment 14 increases torsional stability ofthe component during use in the body, and provides better fill of theproximal intramedulary canal. The outer surface finish of metaphysealsegment 14 may be polished, with a surface roughness average of about 32microinches or less as determined by profilometry. The outer surfacefinish may also be smooth matte or machined using surface preparationtechniques well known in the art. As preferably embodied, the outersurface of metaphyseal segment 14 contains a bone engaging surfacecoating, such as, for example, grit blasted surface, plasma spraycoating, sintered metal bead coating, hydroxylapatite coating, or otherbioactive coatings such as bio-glass ceramics, demineralized bone andcarrier, and growth factor and carrier. The application of such coatingsto metallic implant surfaces is well known in the art. Optionally,metaphyseal segment 14 may be constructed with a distal ring 37. Distalring 37 is a region of raised material equal in thickness to the minimumthickness of the bone engaging coating applied to the outer surface ofthe metaphyseal segment. Distal ring 37 increases the wall thickness ofconical section 31 of metaphyseal segment 14. This in turn will increasethe fatigue strength of conical section 31 by increasing the local wallthickness and shielding it from notches that may result from the porouscoating process. As preferably embodied, distal ring 37 should be usedin smaller sizes of metaphyseal segment 14, wherein the sidewall ofconical section 31 in the vicinity of distal end 14 b may be relativelythin. The local stress levels on conical section 31 that may necessitateuse of distal ring 37 for a particular size of metaphyseal segment 14can be readily determined by persons skilled in the art.

Referring now to FIG. 5, distal segment 16 is formed with a proximal end16 a, a distal tip 16 b, and includes a plurality of sharpenedlongitudinal flutes 40 formed along an incremental length of the outersurface thereof. The sharp edges of flutes 40 dig into the cortical bonewall of the intramedulary canal to increase the torsional stability ofdistal segment 16 during use of the prosthesis in the body. Distalsegment 16 is also optionally formed with a coronal slot 41 beginning atdistal tip 16 b, and proceeding proximally for an incremental lengththereof. Coronal slot 41 increases the flexibility of distal segment 16.This increased flexibility inhibits the concentration of stresses atdistal tip 16 b when the prosthesis is loaded, and allows the prosthesisto better accommodate the curvature of the intramedullary canal. Thoseskilled in the art will recognize that the length of longitudinal flutes40 can readily be adjusted as desired, in light of the overallprosthesis design scheme, to facilitate resistance to torsional loadingson the prosthesis. In the illustrative embodiment of distal segment 16shown in the Figures, the length of longitudinal flutes 40 is about 80%of the overall length of distal segment 16. Advantageously, the sameratio of flute length to distal segment length can be used for all sizesof distal segment 16. Those skilled in the art will also recognize thatthe length of coronal slot 41 can be readily adjusted to provide thedesired degree of flexibility in distal segment 16 without undulycompromising the fatigue strength of the distal segment.

As preferably embodied, distal tip 16 b has a generally parabolic axialcross-section which also serves to reduce contact stresses betweendistal segment 16 and the bone in the vicinity of the distal tip. Asshown in FIG. 6, distal segment 16 has a generally round transversecross-section, but may be constructed with other cross-sectionalgeometries such as, for example, hexagonal or oval. Optionally, distalsegment 16 may be formed with longitudinal channels instead of sharplongitudinal flutes to facilitate both increased stem flexibility andengagement of cortical bone in the intramedulary canal. Although distalsegment 16 shown in the Figures has a straight profile, it may also becurved to better match the natural curvature of the patient'sintramedulary canal. Distal segment 16 is preferably constructed from abiocompatible, high strength titanium alloy, but may also be constructedfrom other biocompatible materials such as cobalt chrome alloy,stainless steel, and composite materials. Further, distal segment 16 ispreferably provided with a polished outer surface finish having asurface roughness average of 32 microinches or less as determined byprofilometry. The distal segment may also be provided with a smoothmatte or machined outer surface finish using surface preparationtechniques well known in the art. To facilitate fixation of distalsegment 16 to the cortical bone wall of the intramedulary canal, ifdesired, distal segment 16 may also be constructed without longitudinalflutes, and instead provided with a porous bone engaging surfacecoating, such as, for example, grit blasted surface, plasma spraycoating, sintered metal bead coating, hydroxylapatite coating, or otherbioactive coating such as bio-glass ceramics, demineralized bone andcarrier, and growth factor and carrier.

Referring now to FIGS. 5 and 8, distal segment 16 is also formed with athreaded bore 42 adjacent proximal end 16 a thereof. Bore 42 isdimensionally configured to threadably engage screw 18 upon insertionthrough the aligned bores of proximal segment 12, metaphyseal segment14, and distal segment 16 (see discussion below). Distal segment 16 isalso formed with a male tapered portion 43 adjacent proximal end 16 a.Tapered segment 43 comprises a conical tapered section 43 a and agenerally parabolic-shaped tapered section 43 b. Male tapered sections43 a and 43 b are dimensionally configured to lockingly engage thecorresponding female tapered sections 34 a and 34 b of metaphysealsegment 14, respectively, upon insertion of proximal end 16 a of distalsegment 16 into bore 32 of metaphyseal segment 14. As here embodied,conical tapered section 43 a has a length of about 0.48 inch, a taperangle ranging from about 1° to about 2.5°, and a blend radius R7 ofabout 0.09 inch. Parabolic tapered section 43 b has a length of about0.09 inch, and a blend radius R8 of about 0.25 inch (see FIG. 8). Forthe foregoing illustrative taper lengths, the ratio of parabolic taperlength to conical taper length is about 19%. The parabolic/conical taperlength ratio should range from about 5% to about 30% to ensuresufficient taper contact area and minimize high point contact stressesat the metaphyseal/distal taper junction. Also, as with the othertapered portions described above, the same taper geometries and blendradii for tapered sections 43 a and 43 b can be used for all sizes ofdistal segment 16 to enhance interchangeability of the distal andmetaphyseal components, and thereby, modularity of the prosthesis 10.

Referring now to FIGS. 7 and 8, cross-sectional views of proximalsegment 12, metaphyseal segment 14, and distal segment 16 are shown tomore clearly illustrate the internal relationship between thesecomponents upon assembly. As shown in the Figures, extension member 24of proximal segment 12 is received in close-fitting, slidingrelationship in bore section 32 a of metaphyseal segment 14, withtapered sections 25 a and 25 b of extension 24 lockingly engagingtapered sections 33 a and 33 b of bore segment 32 a, respectively.Similarly, proximal end 16 a of distal segment 16 is received inclose-fitting, sliding relationship in bore segment 32 c of metaphysealsegment 14, with tapered sections 43 a and 43 b of distal segment 16lockingly engaging tapered sections 34 a and 34 b of bore segment 32 c,respectively. Before a taper lock relationship is established betweenproximal segment 12 and metaphyseal segment 14, the angular orientationof arm 21 and column 22 of proximal segment 12 is established to placecolumn 22 in the desired position to receive a conventional femoral headcomponent (not shown). Upon locking engagement of the complimentarytapered portions of the proximal, metaphyseal and distal segments, bores27, 32, and 42 will be in axial alignment. Thereupon, screw 18 isinserted through the aligned bores into threaded engagement with thecomplimentary threaded section of bore 42. Screw 18 has a countersunkhead 19 receivable in countersink 28 formed in section 27 a ofmetaphyseal bore 27. Screw 18 is securely tightened to further enhancelocking engagement of the proximal, metaphyseal and distal segments ifdesired.

The present invention may be embodied in other forms than disclosed inthe detailed description of the invention without departing from thespirit or essential characteristics of the invention. Accordingly, thedescribed embodiments of the invention are to be considered in allrespects as illustrative and not restrictive. The scope of the presentinvention is therefore indicated by the claims set forth below, and notby the foregoing description of the invention. All modifications whichcome within the meaning and range of equivalency of the claimed subjectmatter are to be embraced within the scope of the claims.

1. A modular hip prosthesis, comprising: a proximal segment, saidproximal segment including a neck lockingly engageable with a femoralhead component, said proximal segment further including a male taperedportion extending distally of said neck; a distal segment having aproximal end and a distal tip, said distal segment including a maletapered portion adjacent said proximal end thereof; a metaphysealsegment having a proximal end and a distal end, said metaphyseal segmentincluding a bone engaging outer surface portion, said metaphysealsegment further including an axial bore therethrough, said axial boreincluding first and second female tapered portions, said first femaletapered portion located adjacent to said proximal end of saidmetaphyseal segment and dimensionally configured to lockingly engagesaid male tapered portion of said proximal segment, said second femaletapered portion located adjacent to said distal end of said metaphysealsegment and dimensionally configured to lockingly engage said maletapered portion of said distal segment; wherein said proximal segmentfurther includes an axial bore therethrough, said proximal segmentengageable with said proximal end of said metaphyseal segment to alignsaid axial bores formed through said proximal and metaphyseal segments,said distal segment further including a threaded axial bore adjacentsaid proximal end thereof, said proximal end of said distal segmentengageable with said distal end of said metaphyseal segment to alignsaid axial bores formed through said distal and metaphyseal segments,said modular hip prosthesis further comprising a screw dimensionallyconfigured to pass through said aligned bores of said proximal,metaphyseal and distal segments and into threaded engagement with saidthreaded axial bore of said distal segment; wherein said distal segmentincludes a bone engaging outer surface portion; and wherein the distaltip of said distal segment has a generally parabolic axial crosssection.
 2. A modular hip prosthesis, comprising: a proximal segment,said proximal segment including a neck lockingly engageable with afemoral head component, said proximal segment further including a maletapered portion extending distally of said neck: a distal segment havinga proximal end and a distal tip, said distal segment including a maletapered portion adjacent said proximal end thereof; a metaphysealsegment having a proximal end and a distal end, said metaphyseal segmentincluding a bone engaging outer surface portion, said metaphysealsegment further including an axial bore therethrough, said axial boreincluding first and second female tapered portions, said first femaletapered portion located adjacent to said proximal end of saidmetaphyseal segment and dimensionally configured to lockingly engagesaid male tapered portion of said proximal segment, said second femaletapered portion located adjacent to said distal end of said metaphysealsegment and dimensionally configured to lockingly engage said maletapered portion of said distal segment; wherein said proximal segmentfurther includes an axial bore therethrough, said proximal segmentengageable with said proximal end of said metaphyseal segment to alignsaid axial bores formed through said proximal and metaphyseal segments,said distal segment further including a threaded axial bore adjacentsaid proximal end thereof, said proximal end of said distal segmentengageable with said distal end of said metaphyseal segment to alignsaid axial bores formed through said distal and metaphyseal segments,said modular hip prosthesis further comprising a screw dimensionallyconfigured to pass through said aligned bores of said proximal,metaphyseal and distal segments and into threaded engagement with saidthreaded axial bore of said distal segment; wherein said distal segmentincludes a bone engaging outer surface portion; and wherein said maletapered portion of said distal segment and said second female taperedportion of said metaphyseal segment each comprise a conical taperedsection blending into a generally parabolic section.
 3. The modular hipprosthesis of claim 2, wherein the ratio of parabolic taper length toconical taper length ranges from about 5% to about 30%.
 4. The modularhip prosthesis of claim 3, wherein the taper angle of said conicaltapered sections of said distal segment and said second female taperedportion of said metaphyseal segment ranges from about 1° to about 2.5°.5. A modular hip prosthesis, comprising: a proximal segment, saidproximal segment including a neck lockingly engageable with a femoralhead component, said proximal segment further including a male taperedportion extending distally of said neck; a distal segment having aproximal end and a distal end, said distal segment including a maletapered portion adjacent said proximal end thereof; a metaphysealsegment having a proximal end and a distal end, said metaphyseal segmentincluding a bone engaging outer surface portion, said metaphysealsegment further including an axial bore therethrough, said axial boreincluding first and second female tapered portions, said first femaletapered portion located adjacent to said proximal end of saidmetaphyseal segment and dimensionally configured to lockingly engagesaid male tapered portion of said proximal segment, said second femaletapered portion located adjacent to said distal end of said metaphysealsegment and dimensionally configured to lockingly engage said maletapered portion of said distal segment; wherein said proximal segmentfurther includes an axial bore therethrough, said proximal segmentengageable with said proximal end of said metaphyseal segment to alignsaid axial bores formed through said proximal and metaphyseal segments,said distal segment further including a threaded axial bore adjacentsaid proximal end thereof, said proximal end of said distal segmentengageable with said distal end of said metaphyseal segment to alignsaid axial bores formed through said distal and metaphyseal segments,said modular hip prosthesis further comprising a screw dimensionallyconfigured to pass through said aligned bores of said proximal,metaphyseal and distal segments and into threaded engagement with saidthreaded axial bore of said distal segment; wherein said distal segmentincludes a bone engaging outer surface portion; and wherein said maletapered portion of said proximal segment and said first female taperedportion of said metaphyseal segment each comprise a conical taperedsection blending into a generally parabolic section.
 6. The modular hipprosthesis of claim 5, wherein the ratio of parabolic taper length toconical taper length ranges from about 5% to about 30%.
 7. The modularhip prosthesis of claim 6, wherein the taper angle of said conicaltapered sections of said proximal segment and said first female taperedportion of said metaphyseal segment ranges from about 1° to about 2.5°.8. A modular hip prosthesis, comprising: a proximal segment, saidproximal segment including a neck lockingly engageable with a femoralhead component, said proximal segment further including a male taperedportion extending distally of said neck; a distal segment having aproximal end and a distal tip, said distal segment including a maletapered portion adjacent said proximal end thereof; a metaphysealsegment having a proximal end and a distal end, said metaphyseal segmentincluding a bone engaging outer surface portion, said metaphysealsegment further including an axial bore therethrough, said axial boreincluding first and second female tapered portions, said first femaletapered portion located adjacent to said proximal end of saidmetaphyseal segment and dimensionally configured to lockingly engagesaid male tapered portion of said proximal segment, said second femaletapered portion located adjacent to said distal end of said metaphysealsegment and dimensionally configured to lockingly engage said maletapered portion of said distal segment; wherein said proximal segmentfurther includes an axial bore therethrough, said proximal segmentengageable with said proximal end of said metaphyseal segment to alignsaid axial bores formed through said proximal and metaphyseal segments,said distal segment further including a threaded axial bore adjacentsaid proximal end thereof, said proximal end of said distal segmentengageable with said distal end of said metaphyseal segment to alignsaid axial bores formed through said distal and metaphyseal segments,said modular hip prosthesis further comprising a screw dimensionallyconfigured to pass through said aligned bores of said proximal,metaphyseal and distal segments and into threaded engagement with saidthreaded axial bore of said distal segment; wherein said distal segmentincludes a bone engaging outer surface portion; and wherein saidmetaphyseal segment has a trapezoidal truncated pyramidal sectionintegrated with a generally conical section.
 9. The modular hipprosthesis of claim 8, wherein said metaphyseal segment has a generallytrapezoidal transverse cross section offset from a generally circulartransverse cross section.
 10. The modular hip prosthesis of claim 8,wherein said metaphyseal segment includes an outer ring formed around atleast a portion of said generally conical section.
 11. A modular hipprosthesis, comprising: a proximal segment having an axial boretherethrough, said proximal segment including a neck lockinglyengageable with a femoral head component, said proximal segment furtherincluding a male tapered portion extending distally of said neck; adistal segment having a proximal end and a distal tip, said distalsegment formed with a threaded axial bore adjacent to said proximal endthereof, said distal segment further formed with a male tapered portionadjacent said proximal end thereof; and a metaphyseal segment having aproximal end and a distal end, said metaphyseal segment including a boneengaging outer surface portion, said metaphyseal segment furtherincluding an axial bore therethrough, said axial bore including firstand second female tapered portions, said first female tapered portionlocated adjacent said proximal end of said metaphyseal segment anddimensionally configured to lockingly engage said male tapered portionof said proximal segment, said second female tapered portion locatedadjacent said distal end of said metaphyseal segment and dimensionallyconfigured to lockingly engage said male tapered portion of said distalsegment; said proximal segment engageable with said proximal end of saidmetaphyseal segment to align said axial bores formed through saidproximal and metaphyseal segments, said proximal end of said distalsegment engageable with said distal end of said metaphyseal segment toalign said axial bores formed through said distal and metaphysealsegments; and said modular hip prosthesis further comprising a screwdimensionally configured to pass through said aligned bores of saidproximal, metaphyseal and distal segments and into threaded engagementwith said threaded axial bore of said distal segment; wherein said maletapered portion of said proximal segment is formed on an extensionmember extending distally of said neck; and wherein said extensionmember includes a nipple member extending distally thereof.
 12. Themodular hip prosthesis of claim 11, wherein said male tapered portion ofsaid proximal segment and said first female tapered portion of saidmetaphyseal segment each comprise a conical tapered section blendinginto a generally parabolic section.
 13. The modular hip prosthesis ofclaim 12, wherein the ratio of parabolic taper length to conical taperlength ranges from about 5% to about 30%.
 14. The modular hip prosthesisof claim 13, wherein the taper angle of said conical sections of saidproximal segment and said first female tapered portion of saidmetaphyseal segment ranges from about 1° to about 2.5°.
 15. The modularhip prosthesis of claim 11, wherein said proximal segment is constructedfrom a material selected from the group consisting of titanium metalalloy, cobalt chromium alloy, and stainless steel.
 16. The modular hipprosthesis of claim 11, wherein said distal segment further includeslongitudinal flutes along an incremental length thereof.
 17. The modularhip prosthesis of claim 11, wherein said distal segment further includesa coronal slot formed along an incremental length thereof.
 18. Themodular hip prosthesis of claim 11, wherein said male tapered portion ofsaid distal segment and said second female tapered portion of saidmetaphyseal segment each comprise a conical tapered section blendinginto a generally parabolic section.
 19. The modular hip prosthesis ofclaim 18, wherein the ratio of parabolic taper length to conical taperlength ranges from about 5% to about 30%.
 20. The modular hip prosthesisof claim 19, wherein the taper angle of said conical tapered sections ofsaid distal segment and said second female tapered section of saidmetaphyseal segment ranges from about 1° to about 2.5°.
 21. The modularhip prosthesis of claim 11, wherein said distal segment is constructedfrom a material selected from the group consisting of titanium metalalloy, cobalt chromium alloy, and stainless steel.
 22. The modular hipprosthesis of claim 11, wherein said distal segment includes a boneengaging outer surface selected from the group consisting of gritblasted surface, sintered metal bead coating, hydroxylapatite coating,plasma spray coating, bio-glass ceramic coating, demineralized bone andcarrier, and growth factor and carrier.
 23. The modular hip prosthesisof claim 11, wherein said metaphyseal segment has a trapezoidaltruncated section integrated with a generally conical section.
 24. Themodular hip prosthesis of claim 23, wherein said metaphyseal segment hasa generally trapezoidal transverse cross section offset from a generallycircular cross section.
 25. The modular hip prosthesis of claim 23,wherein said metaphyseal segment includes an outer ring formed around atleast a portion of said generally conical section.
 26. The modular hipprosthesis of claim 11, wherein said bone engaging surface of saidmetaphyseal segment is selected from the group consisting of gritblasted surface, sintered metal bead coating, hydroxylapatite coating,plasma spray coating, bio-glass ceramic coating, demineralized bone andcarrier, and growth factor and carrier.
 27. The modular hip prosthesisof claim 11, wherein said metaphyseal segment is constructed from amaterial selected from the group consisting of titanium metal alloy,cobalt chromium alloy, and stainless steel.